Fish can be purchased for the Fish Tank in the Captain's Quarters. These will die if not fed between missions (as in ME2). However in ME3, Shepherd can purchase an aquariam at the Citadel which automatically feeds the fish - preventing them from dying. Fish are also carried over on imports of the same character.

Models can be purchased or found for the display case in the Captain's Quarters. In ME3 ships from the model case in ME2 are found scattered through the ship on decks 2-5. All models found and purchased are carried over on imported ME3 saves. Models can be bought in various shops throughout the galaxy.